[GHC] #10009: type inference regression when faking injective type families

[GHC]

#10009: type inference regression when faking injective type families
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        Reporter:  aavogt            |                   Owner:
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.2
       Component:  Compiler (Type    |                 Version:  7.10.1-rc1
  checker)                           |                Keywords:
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  GHC rejects       |               Test Case:
  valid program                      |                Blocking:
      Blocked By:                    |  Differential Revisions:
 Related Tickets:  #10226            |
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Comment (by simonpj):

 Phew! That was ''far'' more work than I expected.

 It's not clear whether to merge this to 7.10
  * It probably won't merge cleanly; but we can probably deal with that if
 necessary
  * It's a big patch, so there's always a risk of messing something else up

 It fixes: #10009, #10226, #10340.

 Opinions?

 Simon

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10009#comment:24>
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